as Ricoh has introduced the new 30mm and 40mm eyepieces for the XW series, I became curious what the optics difference between the both might be,
https://web.archive.org/web/20141231092 ... xw/61.html
http://www.ricoh-imaging.co.jp/english/ ... index.html
An easily recognizable difference in the lens form and groupings can be seen on the 40mm and 30mm XW eyepieces.
The last group in the old XW 40mm includes three lenses, with its first lens flat out, followed by a double concave lens, and finally by a biconvex eye lens.
In the new XW40-R version, the last two lenses are cemented into the eye doublet.
The last group in the old XW30 includes again three lenses, with its first lens flat out, followed by a double concave lens, and finally by what's looking like a meniscus eye lens convex out.
In the new XW30-R version, the last group begins with a cemented doublet, followed by a meniscus eye lens.
Herewith the new XW40-R and XW30-R are replacing two lenses with a doublet, and flip this doublet for the both focus lengths.
These differences may be due to the economic availability of the special glass materials, as this economic availability changes with time.
During one of the last shoppings at Intercon Spacetec, I have added the old
The most difficult nebulae will be still observed within the small
Thank you for reading,
JG